Mandelbrot.cc

#include <GL/glut.h>
#include <complex>
using namespace std;

constexpr int w_width=640,w_height=640,countnum=100;
double dx,dy;

int convergence(const complex<double>&);

void init();

void display();

void resize(int,int);

int main(int argc,char **argv){
  glutInit(&argc,argv);
  glutInitDisplayMode(GLUT_RGBA);
  glutInitWindowSize(w_width,w_height);
  glutCreateWindow(argv[0]);
  glutDisplayFunc(display);
  glutReshapeFunc(resize);
  init();
  glutMainLoop();
  return 0;
}

int convergence(const complex<double>& c){
  complex<double> z(0,0);
  int count;
  for(count=0;count<countnum;count++){
    z=z*z+c;
    if(norm(z)>4.0) break;
  }
  return count;
}


void init(){
  glClearColor(1.0,1.0,1.0,1.0);
}


void display(){
  glClear(GL_COLOR_BUFFER_BIT);
  glLoadIdentity();
  glTranslatef(0.5,0,0);
  glBegin(GL_POINTS);
  for( double x=-1.5;x<=0.5;x+=dx){
    for( double y=-1.0;y<=1.0;y+=dy){
      int count=convergence(complex<double>(x,y));
      float color=1.0-(float)count/countnum;
      glColor3f(color,color,color);
      glVertex2d(x,y);
    }
  }
  glEnd();
  glFlush();
}
void resize(int w,int h){
  dx=1.0/w,dy=1.0/h;
  glViewport(0,0,w,h);
  glMatrixMode(GL_PROJECTION);
  glLoadIdentity();
  gluOrtho2D(0,w/w_width,0,h/w_height);
}